Three-dimensional boundary layer flow phenomena such as attachment, separation, vortex flow and laminar-to-turbulent transition have been difficult to measure in practical applications. Traditionally, flow visualization techniques have been used to determine three-dimensional flow separation regions on bodies in motion. Some success has been achieved in obtaining laminar and turbulent separation in two-dimensional flows. Currently, however, there are no techniques available to determine bifurcation regions in realistic three-dimensional flows.
Such flow situations exist in many practical applications including airflow over external surfaces such as aircraft fuselages, wings, empennage, automobile bodies, etc, and on internal surfaces, such as jet engine inlets, automobile intake diffusers, etc. It is often necessary to determine flow effects such as separation and reattachment in varying conditions in order to properly design and control the airflow over and around these bodies. Similar situations exist in the case of water, fuel, or other liquid flow over marine vehicle bodies such as submarine and ship hulls, keels, and through ducts and pipes.
All of these flow conditions result in three-dimensional boundary layer phenomena such as turbulence, flow separation and reattachment, and vortex distribution. There is a need for a sensing system and methodology for identifying and characterizing these phenomena for a three dimensional body under real flow conditions without breaching the structural integrity of the body's surface.